Manufacture of detachable blades



July 14, 1931. m. P-ARKER- 14,1 2

MANUFACTURE OF DETACHABLE BLADES Original Filed March 7; 192'? & w & m

- a 3 52: lm $9 INfiNTOR BY PM, f I. ATTORNEYS 59 fine a helical or tPatented July 14, 1931 UNITED STATES MORGAN PARKER, OF NEW YORK, N. Y.

MANUFACTURE OF DETAOHABLE BLADES Original application filed March 7,1927, Serial No. 173,528. Divided and this application filed February20, 1828, Serial No. 255,722. Renewed flctober 2, 1930.

This invention relates to the manufacture of replaceable blades orcutting edges for scissors. Scissors and shears which are in constantuse must be continually resharpened. This is not only expensive andtimeconsuming, especially if the blades are ground to a properlyserrated cutting edge, as for barbers shears, but after a time thegrinding wears the blades to such a condition 1 that the scissors mustbe discarded. In some instances too it may be diflicult to secure theservices of a skillful grinder,-so that the scissors must either bepoorly ground or be used when too dull for efficient cutting.Furthermore, the blades of the common type of scissors should be madeofhigh grade cutlery steel throughout if they are to present and retain akeen cutting edge after each grinding. This is expensive and involvesdropforging difficulties.

It was early recognized that a two-part blade would solve some of thesedifficulties. A tool steel cutting blade welded or mechanically attachedto a softer metal shank simplifies the drop-forging problem and makes acheaper instrument, but the resharpening problem still persists. Suchblades when mechanically secured to the shank, are comparatively heavy,are ground to shape like any scissor blade, and are too costly to bediscarded rather than resharpened. The welded blade becomes, of course,an integral part of the shank, and the completed instrument thereforepresents no advantages over scissors having blades of tool steelthroughout.

The practical utility of inventions of this class requires that thescissors shanks and blades be of such design and construction as topermit of a low initial cost of production;

the cost of replacement blades to the user should be considerably lowerthan the ex pense of grinding; the blade should be readily and securelyattachable to the shank and conveniently detachable therefrom, withoutthe use of tools and by persons unskilled in mechanical matters; andthis attachment should be possible Without taking the shanks apart orremoving the king-pin.

The cutting edges of scissors commonly de= .aree dimensional curve, the

curvature depending upon the type of scissors and the work for whichthey are designed. To grind this curve into each blade would involve aprohibitive expense Where the blade is to be discarded after the firstdulling, and I therefore make my blade straight, but so flexible as tobe conformable to any curve or twist normally defined by the permanentshank on which the blade is mounted. To mount this blade in cuttingposition each shank is provided with a longitudinal bead or undercutrail extending along its operative edge and conforming to its curvature,and each blade is provided with a corresponding longitudinal slottedrecess. The blade can therefore be slid lengthwise over the bead, andbecause of its universal flexibility, conforms perfectly to thecurvature.

The blade of the present invention, in order that it may possess theuniversal flexibility so important if it is to conform to the curvatureof the shank is of small transverse dimensions-thus a blade for barbersscissors of average size is about 5/64 of an inch high and about 1/32 ofan inch wide. Such a blade is indeed a specially shaped steel wire.According to the present invention I have provided a method wherebysucha wire can be rolled, drawn, tempered, ground and out tolength in acontinuous operation.

In the accompanying drawings I have illustrated the various stepsfollowedin making the blade.

In these drawings Figure 1 is an enlarged section of one form of thematerial from which the blade may be made; Figure 2 is an enlargedfragmentarysection ofa pair of rolls for preliminarily forming thematerial shown in Figure 1;-Figure 3 is an-enlarged section showing theform of the blade material after having passed through the rolls shownin F igureQ; Figure is an en largecl fragmentary section of a secondpair of rolls and an enlarged elevation of a coacting mandrel andsupport therefor, for fur- V ther forming the blade material; Figure 5is a an enlarged section showing the form of the blade material afterhavingpassed through the rails over the shown in Fig ure 4; Figure 6 isan enlarged fragmentary view of chilling dies for hardening andplanishing the blade material; Figure 7 is an enlarged section of amodified form of material from which the blade may be drawn; Figure 8 isan enlarged fragmentary section of a pair of rolls for handling'thematerial of Figure 7; Figure 9 is an enlarged secthe blades aremanufactured in lengths in the following manner: Material of triangularcross section such as shown 1n Figure 1 ..is passed, either hot or'annealed, through rolls 1''1 (Figure 2), bringing it to the gen- ,25.eral form shown in {Figure 3; I It is then reheated or re-annealed' andpassed between rolls 2-2 (Figure h and over'inandrel 3, "mountedin'support a (Figure 1 4c) thereby bringing it to the form shown inFigure 5.

30 After passing through rolls 22 and over mandrel 3 and while still hotor a'fter ,ha-ving'been re heate'd by passing througha hardfningfurnace,as drawn through dies 5 and over mandrel 6"(Figure'6). These dies arepreferably formed with a bell-mouth entrance7, and may be of thewater-cooled type.

Their function'is to chill, harden and planish the strip and i preventdistortion thereof. :LThereafter the strip maybe tempered'in any 40well-known manner, as by feedingit through a-bath of heated oil. ;Onaccount of "the small cross-sectional area and consequent-lack ofrigidity of the strip while "hot, it may be found desirable to feed'itdownward, rather ,45 than horizontally,through the forming rolls.

"After'being tempered, the strip is fed into contact withan abrasivewheel, which grinds 'the face 8 to form'the cutting edge 9. Any

cut outs and notches required to facilitate the mounting of the bladeupon the-scissors shank as' illustrated my c'o-p'ending application;Serial No. 173,528, are then ground oit and the blades out to lengthalso by a grinding operation. 4

""InF-gure 7 's shown a material of somewhat different initial shape.This is Similarly passed while hot or annealed through rolls 101O(Figure 8),-bringing i t tothe intermediate formshown in'FigureIQQ In Ethis intermediate form it is drawn through a furnace and thencethroughdies 1111 (Figure 10) and over-mandrel 12 to drawclose it .to the formshown in Figure 11 and to chillyharden and planish the material in Vefih such form) It willbe noted that with this modified method, thepassage of the strip material through one set of rolls is eliminated,thus rendering the process more economical.

The blades may be so cheaply made by this method that when dulled theycan be replaced for much less than cost of re- This application is adivision of my cop'ending application, Serial No. 173,528, filed March17', 1927:" i

I claim: 1. The'method of making detachable blades for scissors whichcomprises passing a continuous strip of- -metalbetween" rolls to form acontinuous slotted recess extending longitudinally therethrough, drawingthe shaped strip through hardening and planijshi ng dies, tempering. thestrip, grinding a cuttingedge thereonand then cutting are strip into u'nit lengths- 1 2. The method of making detachable blades for scissorsin a continuous"operationwhich consistsin passing a wiredike strip ofmetal downward between rolls to form a longitudinal passagetherethrough, heating such slotted strip' by passing it through'affurn'ace,

hardening and "polishing by drawing it through dies, tempering andgrindi g a putfting edge thereon andthen cutting' thels tr ijp into'unitlengths."

ftestimony'whereof I aflix my signature."

' MQBGAN ITe iKEB

